Polar optical phonons in semiconducting CdS nanocrystals

Belogorokhov, A. I.; Belogorokhov, I. A.; Miranda, R. P.; Vasilevskii, M. I.; Гаврилов, С. А.

doi:10.1134/s1063776107010128

Cited by 5 publications

(4 citation statements)

References 14 publications

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“…For CdS film, the most intensive mode is observed at a frequency of 302 cm -1 and is associated with LO phonons [51][52][53]. In addition to this peak, a line of overtones of LO phonon with a reduced intensity appears at the doubled frequency 2LO (at ~ 602 cm -1 ), which is in agreement with the literature data [54].…”

Section: Raman Spectroscopysupporting

confidence: 90%

Formation of CdxPb1−xS/Cd1-δS thin-film two-phase compositions by chemical bath deposition: composition, structure, and optical properties

Маскаева

Vaganova

Марков

et al. 2021

J Mater Sci: Mater Electron

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The possibility of forming thin-film two-phase compositions CdxPb1-xS/Cd1-S by using the chemical bath deposition from aqueous media with adding various cadmium salts has been demonstrated. The crystal structure, chemical composition, morphology, and the band gap were studied by the X-ray diffraction, scanning electron microscopy, elemental analysis, Auger and Raman spectroscopy, and diffuse reflectance measurements. The formation of a CdxPb1-xS/Cd1-S substitutional solid solution phase in well-faceted crystallites on the substrate of an X-ray amorphous CdS phase has been experimentally proved. The found differences in their composition are the result of the effect of the nucleophilicity of the anionic component of the cadmium salt on the kinetics of thiourea decomposition. The results demonstrate the possibility of forming thin-film two-phase compositions or heterostructures on the base of cadmium and lead sulfides in one technological stage by using chemical bath deposition, which can be important for the creation of solar cells.

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Section: Raman Spectroscopysupporting

confidence: 90%

Formation of CdxPb1−xS/Cd1-δS thin-film two-phase compositions by chemical bath deposition: composition, structure, and optical properties

Маскаева

Vaganova

Марков

et al. 2021

J Mater Sci: Mater Electron

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“…The appearance of both SO and TO confined modes in ultra-small (1.8 nm) sized CdS NCs accomplished with disorder-activated phonons was reported in [77]. With increasing average NC size, the effects of dimensional quantization on the phonon modes [84] become less significant and the character of the absorption spectrum aspires to its 'classical' shape, with absorption maxima at the Fröhlich frequency and at a TO phonon frequency. In addition, increasing NC concentration causes a frequency shift of the SO mode to the TO mode frequency, which was explained as being due to the dipole-dipole interaction between NCs [79].…”

Section: Ir Absorption By Confined Phononsmentioning

confidence: 90%

“…However, for relatively thick NC coverages, the entire 'reststrahlen' band is observed [82]. Surface optical (SO) phonons (which are typically seen in Raman spectra as a weak shoulder) become dominating, sometimes even structured, features in IR spectra [39,80,83,84]. The frequency positions of the SO modes which are located between the frequencies of TO and LO phonons are sensitive to the dielectric function of the media surrounding the NCs [80].…”

Section: Ir Measurementsmentioning

confidence: 99%

Vibrational spectroscopy of compound semiconductor nanocrystals

Dzhagan

Azhniuk

Milekhin

2018

J. Phys. D: Appl. Phys.

107

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A review of recent applications of Raman spectroscopy as a fast, sensitive, and non-destructive technique for exploring II–VI semiconductor nanocrystals fabricated by various methods (colloidal chemistry, Langmuir–Blodgett method, diffusion-limited growth) is presented. Specific size-related features revealed in the nanocrystal Raman spectra (phonon confinement, surface phonons) are analysed, as well as more complicated size effects for ultrasmall nanocrystals (NCs) related to the activation of the phonon density of states modified by surface reconstruction. Similarities and differences of the Raman scattering in II–VI and III–V or elemental (Si) semiconductor NCs are briefly analysed. Implementation of resonant conditions and application of infrared absorption analysis, complementary to the Raman spectroscopy—resulting in the observation of phonon modes ‘silent’ in conventional Raman scattering processes—are discussed. Furthermore, Raman spectroscopy is employed for fast and efficient assessment of the composition of matrix-embedded ternary II–VI nanocrystals, as well as more complicated multimode quaternary II–VI systems. Selective probing of electronic and vibrational spectra of different parts of heterogeneous NCs (such as core–shell systems) by tuning the excitation wavelength in resonant Raman scattering is considered. The analysis of phonon spectra is applied to the quantitative estimation of strain in the core and shell, and degree of interface intermixing, as well as to checking the surface oxidation. The above approaches and phenomena are further explored in more complex compound NCs beyond II–VI, such as CuInS2/ZnS. Recent results in the field of surface- and tip-enhanced Raman spectroscopy and surface-enhanced infrared absorption are analysed showing the perspectives of Raman spectroscopy as a tool for investigation of single-nanocrystal phonon spectra.

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“…Most of the experimental studies of optical phonons in QDs have been performed by Raman spectroscopy [1][2][3][4][5]. Quantum-size effect on optical phonons can also be seen by far-infrared (FIR) spectroscopy [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%